The eight o'clock hour arrives on the Murph & Mac Show and with it comes a plea from the hosts of the breakfast programme at KNBR, San Francisco's most popular sports talk radio station. "We're taking your calls on the World Cup,'' says Brian Murphy, whose love and knowledge of sport extends, almost uniquely for someone in his position, to "soccer".

KNBR's breakfast king may indeed be taking calls on the World Cup, but the bad news is punters are not making many of them. "We did a segment last week on nicknames – I was inspired when I read the Ivory Coast were also known as Les Eléphants – and we had a few calls," Murphy says before a wistful note creeps into his voice. "But overall I would have to classify general interest in this World Cup as mild." On this occasion, "mild" might be classified as a mild over-estimation.

Eventually, a self-styled soccer expert calls to discuss the impact Freddie Adu will have in South Africa, a conversation that might have given Murphy hope were it not that Adu, the one-time boy wonder of American soccer, is not even a member of the US squad this year.

It was ever thus in the star-crossed relationship between beautiful game and the United States. If the enthusiasts are confused, then what chance do the sceptics have and, more to the point, what chance do the enthusiasts have of convincing the sceptics they should care about what will happen in South Africa over the next month or so?

Still, on the cusp of what promises to be a captivating tournament, Murphy refuses to concede defeat and in this he is not alone. ESPN, the television network that dominates the American sporting landscape, has spent $100m (£68m) on the broadcast rights to the 2010 World Cup (and including the 2014 tournament) and has put together a 300-strong team to cover the event. It will broadcast more than 200 hours of programming – half devoted to live games, the other half to studio discussions from South Africa. As for the network's marketing campaign – to describe it as ubiquitous would seriously underplay the scope and persistence of its message.

The answer is that there is no trickery involved, simply a corporate belief that America is at long last about to embrace fully the global game. "We have a production plan that we think is up to the level of ambition of this event with a great group of commentators that we've assembled, a broadcast operation that is far and away the biggest we've ever amassed outside of the US," says Jed Drake, the executive producer of the network's World Cup coverage.

Along with Martin Tyler, Steve McManaman and Roberto Martínez, Alexi Lalas, who played in two World Cups for the United States, is a member of the ESPN broadcast team in South Africa, so he is hardly likely to accentuate the negative when it comes to America's appetite for the sport but he does at least give a convincing explanation for the apparent gulf in World Cup enthusiasm between the broadcaster and its audience.

"There might not yet be a vast army of American soccer fans but there is certainly a vast army of soccer fans in America. They might not be calling into sports talk radio because that is where fans of traditional American sports are more like to be heard. But soccer fans are out there, trust me; on the blogs, in chat rooms, on Facebook – where the future is," he argues.

Corporate America seems to agree. Name a household brand – Coke, McDonald's, Nike – and you will find it attached to some form of World Cup campaign. Indeed, a recent poll for the Sports Business Journal concluded that soccer has the biggest growth potential of any major sport, while Business Week magazine boldly declared "America Loves Soccer".

In the face of such an onslaught, the temptation is to give in and simply accept what the multinationals and the vested interests are saying; that, finally, America really has fallen in love with soccer. But the truth is more, and less, complicated than that. In the week building up to the US team's opening match, against England, coverage in the mainstream sporting media has been virtually nonexistent. If there are injury scares or tensions in the camp then no one knows or cares in San Francisco, where the conversation is focused on the chances of the Giants, the city's baseball team, making the play-offs and proposals to build a new stadium for the 49ers, the city's NFL team.

Meanwhile, the national sporting conversation has been dominated by the NBA finals and by Stephen Strasburg, a young pitcher for the Washington Nationals whose winning debut performance on Tuesday evening actually exceeded the hype that preceded it. "Historic" was one of the more restrained adjectives being bandied around.

Landon Donovan, or any other member of the USA team, can only dream of such attention. For the moment at least. "A victory over England, which I believe is very possible, could change everything," Lalas says. "If that happens then you will really see the casual fan take an interest."